The event will include live music, barbecue and Montana beers and wine, according to a copy of the invitation obtained by CQ Roll Call. The party's two other top elected officials in the state, Sen. Jon Tester and Gov. Steve Bullock, are co-hosting the event with Baucus.

According to a Montana Democratic source familiar with the guest list, there will be about 400 donors in attendance at the evening gathering to benefit the state party. Those giving $1,000 get "platinum sponsor" status, but $50 per adult is enough to partake in the event.

The Democratic source said Baucus has already helped raise $200,000 for the state party this year, and Saturday's event is expected to bring in more than it ever has before on the party's behalf. The annual event has also previously raised money for the campaigns of Baucus and Tester.

"Whoever the eventual candidate is will have the aggressive fundraisers and politically savvy teams of Max Baucus, Jon Tester and Gov. Bullock in their corner — three guys who know what it takes to win in tough years, so I wouldn’t write off that Senate seat anytime soon," the source said.